Procharger's i-1 Variable Ratio Supercharger - Intelligent Design

An inside look at ProCharger’s variable-ratio supercharger

When it comes to making fast cars really fast, and really fast cars almost scary, nothing beats boost. We doubt this little tidbit of truth is a revelation to any of you and it's certainly common knowledge around the ProCharger offices. For sometime now, the company has been building kits to stuff tons of atmosphere into our engines, and recently it came up with a new idea—programmable power. Before now, if you wanted your supercharger to put out more, or less, boost you needed to grab some tools, pop the hood, and change out a pulley and possibly a belt. But, ProCharger's i-1 system makes modifying your boost curve as easy as typing on a keypad. Hell, you don't even have to open the hood and that's the kind of instant gratification that made this country great.

The i-1 works thanks to a very durable dry hybrid CVT drive system which features a continuously variable transmission. A high-torque electric motor drives the CVT sheaves in and out to change the supercharger's ration, which adjusts boost throughout the engine's rpm curve. The electric motor is controlled by a cockpit-mounted control system (either a simple three-way switch, or the optional, and programmable touchscreen). Boost for a given engine is dictated by the supercharger drive ratio, engine rpm, and the resulting impeller rpm. Because the system can control boost output in 250 rpm increments, it allows the power to come on in line with the car's ability to get it to the asphalt. Toss on some sticky drag tires, set the system in competition mode, and hit the track. Hand the car off to someone not accustomed to high power and you can lock it in touring mode, which provides almost no boost. The CVT drive gives the system unheard of flexibility and it's a hell of a lot easier than swapping blower pulleys all the time.

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01. The i-1 does everything a typical P-1SC-1 supercharger does and more, so it shouldn’t be a surprise that it’s larger. That weight is worth every pound considering the benefits of being able to adjust the boost from the driver seat. A complete satin-finished system for a C6 Vette runs around $8,000. Polished and blacked out units are available for a few bucks more.

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02. As with all ProChargers designed in the last 14 years, the i-1 features self-contained oiling for easier installation. Here’s what the guts look like with the top cover removed. To keep the packaging compact, all the internals are “scaled down” a bit compared to a P-1SC-1.

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03. ProCharger utilizes premium components for the i-1 including 7075 T6 aircraft-grade aluminum for the impeller. It also incorporates precision high-speed bearings, AGMA 12 gearsets, and billet housings. An electric motor moves a cone that changes the length of the belt and thus changes the ratio of the supercharger.

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04. One key to the durability of the unit is the dry hybrid belt. It’s something you really need to hold in your hand to appreciate its construction. The belt is very mechanically efficient and the drive system can be programmed to change the overall supercharger ration by four times, in 250 rpm increments. The dry hybrid belt is projected to last 7 to 10 years in this application and zero maintenance is required. The belt is cooled by a stream of air that’s fed to it from the induction system.

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05. A precision, permanent magnet electric motor is used to change the blower ratio. As with everything else in the system, ProCharger worked to get this component as small, and rugged, as possible.

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06. Another key component of the i-1 that was scaled down, is the impeller. Smaller than the one found in a P-1SC-1, it’s still able to produce 900 hp by spinning at a higher rpm. As ProCharger’s Ken Jones told us, “Generally speaking, higher rpm compressors are also able to achieve higher efficiency, and thus an intercooled i-1 produces the most power per pound of boost. For example, with only 7.5 psi, a complete i-1 system routinely produces a gain of more than 190 rwhp on otherwise stock LS3 engines, running high quality pump gas.”

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07. Since the i-1 interfaces with the engine’s ECU, it’s only available for cars with an OBD-II port. The control box mounts under the dash and plugs into the OBD-II port (red plug) and ProCharger provides a new male port for use with handheld programmers.

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08. Like all ProChargers, this unit incorporates an air-to-air intercooler. According to ProCharger, this is less complex and easier to install, and more efficient, than air-to-water (actually air-to-water-to-air) intercooler. Installation location is the same as their P-1SC-1 kits.

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09. As Ken explained, “The i-1 ProCharger, when purchased as a complete system, comes pre-programmed from the factory with three performance modes: Touring, Sport, and Competition. With the purchase of the optional touchscreen ($395), password protection can be enabled as well as the custom mode, which can be programmed in 250 rpm increments. This Custom mode is frequently used for road racing. With the purchase of a tuner kit, where the ProCharger factory is not providing the engine calibration, dealers and customers can custom program all four modes to any boost level and boost curve they desire.”

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10. Touring locks the supercharger at a minimum ratio to deliver maximum fuel economy, better driveability for bad road conditions, and also to provide a “valet mode.” It’s also handy if you want to let someone borrow your ride. Again, changing the modes can be password protected if you like.

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11. Sport mode is the typical daily driving mode, and delivers a boost curve that comes on a bit slower so that street tires can hook up. You still get max boost, it just ramps up in a more gentle fashion.

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12. Competition mode provides a flatter boost curve, and is intended for use with sticky tires. In this 1:1 ratio mode, boost comes on just like a regular ProCharger, like the P-1SC-1.

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13. The touchscreen can also be configured to show a host of engine information with the user being able to set up four separate screens.

Touring

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Sport

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Competition

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14. The best way to see how the unit can change was to strap a C6 to the dyno and make some pulls. In Touring mode you can see that only 1 pound of boost is fed to the engine and thus the rear wheel hp number is nearly stock at 375 hp. In Sport mode you get the full 7.9 pounds of boost, but if you compare the curve to the Competition mode graph you can see that the boost comes on gradually which helps less-than-sticky street tires from spinning into clouds of molten rubber.

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15. While at the ProCharger factory we spied them doing prototype fitment of the i-1 ProCharger in a C7 Vette. The larger size was a challenge, especially since they wanted to make sure items like the ABS module wouldn’t have to be moved, but what we saw looked very promising. vette

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